They are a type of locking nuts.
You photo makes them look REALLY oval but they should be fine.
You should be able to screw them on by hand a few turns till they hit the smashed (oval) part then it will take more force.
They work like this type of lock nut.
The dimple compresses the threads and that puts force on the bolt.
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If it makes you nervous a high temp Nyloc nut would work.